One type of packaging for sterile medical devices uses a double sterile package having a sealed primary package that contains the device and a secondary sealed package. The primary package is contained inside the secondary package, with the contents of both packages being in a sterile condition. Certain types of materials from which medical devices are made must be sterilized by ethylene oxide, because the preferred mode of sterilizing via gamma radiation causes excessive degradation of such materials. Polypropylene and synthetic absorbable polymers such as polyglycolic acid and poly-(p-dioxanone) are illustrative of such materials that undergo an undesirable degree of degradation upon exposure to a sufficient dose of gamma radiation to effect sterilization.
A typical package of this type adapted for ethylene oxide sterilization employs a sealed metal foil pack as the primary package, and as the secondary package a relatively rigid tray having a cover of a material that is impervious to bacteria but which is pervious to ethylene oxide gas. Spunbonded polyethylene (such as duPont's TYVEK) is illustrative of such materials. The sterilization procedure used with such a package would ordinarily employ two cycles. Initially, the foil pack containing the medical device to be sterilized is partially sealed, is then sterilized with ethylene oxide gas, and the seal is completed in a sterile atmosphere. The foil pack is then sealed in the secondary package containing an ethylene oxide-pervious cover, and the package as a whole is then subjected to a second ethylene oxide sterilization step.
This invention provides a double sterile package that can be sterilized by ethylene oxide gas in one sterilization cycle.